Report on Kilauea (United States) — 28 July-3 August 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 July-3 August 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Kilauea (United States). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 28 July-3 August 2004. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
An episode of deformation consisting of deflation, inflation, then deflation began at Kilauea on the morning of 27 July. It was accompanied by increased surface activity at several places. During inflation, seismicity greatly increased below Kilauea's caldera. Field observers reported that deformation may have occurred at the S flank of Pu`u `O`o. Several surface lava flows were visible on the coastal flat during 28 July to 2 August, and lava continued to flow into the sea. Aside from the deflation-inflation-deflation event, seismicity was weak beneath Kilauea's summit and tremor at Pu`u `O`o was at moderate-to-high levels.
Geologic Background. Kilauea, which overlaps the E flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 km2, destroying nearly 200 houses and adding new coastline to the island.